Safety device for airless spray guns



Jan. 9, 1968 l R. E. PARKE ETAL 3,362,644

SAFETY DEVICE FOR AIRLESS SPRAY GUNS Filed March 7, 1966 5 y l ftd/@H4152 e @wav/Wl( United States Patent O 3,362,644 SAFETY DEVICE EUR AIRLESS SPRAY GUNS Robert E. Parke, Fridley, and Michael R. Russinik, Minneapolis, Minn., assignors to Gray Company, Inc., Minneapolis, Minn., a corporation of Minnesota Filed Mar. 7, 1966, Ser. No. 532,370 12 Claims. (Cl. 239-142) This invention relates to an improved airless spray gun for spraying fluids, such as paints and hydramastic materials, and more specifically relates to an improved airless spray gun that includes novel means for diffusing and dispersing Huid inadvertently or accidentally discharged from the spray gun While the spray tip thereof is removed, thereby significantly lessening the possibility that the uid can penetrate a persons skin.

In typical industrial airless spray painting operations, the pressure of the paint in the spray gun may be between 1200 and 1600 p.s.i. When airless spray guns are used to spray more viscous hydramastic materials, such as undercoating, the pressure of the material in the gun may be as high as 3000 p.s.i. Of course, under normal conditions, the liuid emitted through the spray tip of the gun is in the form of a tine, relatively low pressure mist or spray, and there is no appreciable danger of this spray penetrating a persons skin.

However, when the spray tip is removed from the gun, for example, for cleaning or for the replacement of the tip, any tiuid emitted from the gun would be in the form of a concentrated, relatively high pressure and velocity stream.

Obviously, during the cleaning and replacement of the spray tip, there is always a possibility that the spray gun may be accidentally triggered. And on occasion, the fluid stream thus emitted from the gun, has penetrated the skin of a person handling or near the gun, causing severe injury to that person.

One proposal to eliminate this hazard is disclosed in United States Letters Patent No. 3,181,798 granted to Wahlin et al. on May 4, 1965. fIn this patent, Wahlin et al. disclosesthat if a transverse slot is milled on the downstream side of the valve seat member so that the slot intersects the central fluid passage in the valve seat member, any uid stream accidentally emitted from the gun, while the spray tip is removed therefrom, will be spread as it passes through the valve seat member. This spreading action is said to diffuse the fluid stream and thereby lessen the possibility that the fluid stream will be able to penetrate a persons skin. However, it has been found that a superior dispersion or diffusion of the fluid stream may be obtained, particularly at the high pressures used in spraying hydramastic materials, if a plurality of pins are disposed in the path of the fluid stream downstream of the fluid control valve. These pins are arranged so that they extend through the longitudinal central axis of the Huid passage interconnecting the lluid control va'lve and the spray tip of the gun. This arrangement of the pins insures the complete diffusion and dispersion of any fluid stream accidentally discharged from the gun while the spray tip thereof is removed and thereby eliminates, for all intents and purposes, the danger that the fluid will be able to penetrate a persons skin and thus cause injury.

Accordingly, it is a primary object of the present invention to provide an improved airless spray gun that includes a novel fluid dispersion means which is positioned in the uid passage interconnecting the fluid control valve and the spray tip to disperse and dilfuse any fluid accidentally emitted from the gun While the spray tip thereof is removed.

Another object of the present invention is to provide an improved airless spray gun that includes a novel fluid dispersion means comprising at least one pin which is positioned in the fluid passage interconnecting the uid control valve and the spray tip and which projects into the passage to diffuse and disperse any uid accidentally emitted from the gun while the spray tip is removed. l Another object of the present invention is to provide an improved airless spray gun that includes a novel fluid dispersion means comprising a plurality of pins which have their ends mounted in the side of the passage interconnecting the fluid control valve and the spray tip in the gun and which project into the passage and pass through and are perpendicular to the longitudinal central axis of the passage.

A still further object of the present invention is to provide an improved spray gun that includes novel iluid dispersion means comprising three pins which are secured in the uid passage interconnecting the fluid control valve and the spray tip in the gun and which project into the liuid stream in the passage to disperse and diffuse the fluid emitted from the gun, while the spray tip is removed, thereby preventing the emission from the gun of a concentrated, high pressure and velocity fluid stream. A related object of the present invention is to provide an improved airless spray gun in which the three pins, comprising the novel uid dispersion means, are displaced from each other by an angle of 60 degrees and are spaced from each other, along the longitudinal axis of the fluid passage.

Another object of the present invention is to provide an improved spray gun that includes novel liuid dispersion means which may be relatively inexpensively manufactured, which will not interfere with the normal functioning and operation of the spray gun Whi'le the spray tip is mounted thereon and which may be used with conventional airless spray guns without modification of the structure of the guns.

These and other objects and advantages of the invention will become apparent from the following description of the preferred embodiment of this invention, described in conjunction with the the following drawings, in which:

FIGURE 1 is a partial vertical cross-sectional view of the improved airless spray gun of the present invention;

FIGURE 2 is an enlarged, partial vertical cross-sectional view of the forward end of the spray gun, the fluid control valve and the spray tip assembly;

FIGURE 3 is an enlarged, vertical cross-sectional view of the housing for the novel dispersion means of the present invention; and

FIGURE 4 is a plan view taken along lines 4 4 in FIGURE 3.

Referring now to FIGURE 1, the improved airless spray gun 10 of the present invention comprises a body 11 which is generally shaped in the form of a pistol and includes a handle portion 12 and a barrel portion 13. A spray tip assembly 14 is mounted on the forward end of the barrel portion 13. A trigger 15 is pivotally mounton the body 11, as hereinafter described, and movement of the trigger 15 toward the handle 12 opens the uid control valve in the spray Igun and permits fluid to be sprayed from the gun in the conventional manner. The body 11 also includes a guard 16 to protect the trigger 15 and an integral hook portion 17 for storing the gun when not in use.

The spray gun lll communicates with a pump or other source of fluid under pressure, shown schematically at 18, through a hose or conduit means 19. The end of the hose 19 is connected with the handle 12 by means of a fitting 20 which permits liuid communication between Et the -hose 19 and a passage 21 formed within the handle 12.

The passage 21 extends through the handle and into a main cavity 22 formed in the body 11. A uid control Valve, shown generally at 23, is completely positioned Within the cavity 22 and is operatively connected with trigger 15, as hereinafter described. The main cavity 22 includes a recess 24 and has a threaded opening 25 through which the valve 23 may be removed for repair and cleaning. A threaded cap 26 normally closes the opening 25 and a sealing ring 27 prevents leakage therebetween.

A square shaft 2S extends transversely through the body 11 and recess 24. The upper, bifurcated ends (not shown) o'f the trigger 15 are connected to the ends of the shaft 2d which project beyond the body 11 whereby movement of the trigger, from the position Shown in FIGURE 1, toward the handle 12 causes a counterclockwise rotation of the shaft 28. Likewise, movement of the trigger from a position adjacent to the handle 12 to the position shown in FGURE l causes a clockwise rotation of the shaft. Sealing means (not shown) prevent leakage of iiuid from the cavity 22 along the shaft 28.

A crank arm 29 is mounted on the shaft 2S, intermediate the ends thereof and is positioned in the recess 24 for limited rotational movement therein. The crank arm 29 has a lower bifurcated end 30 which extends into the main cavity 22 and is operatively connected with the valve 23 as hereinafter described.

The valve 23 includes a shaft 3l that carries a ball 32 at its forward end 33. The ball 32 may engage a valve seat member 34 positioned in the forward end of the cavity 22. The shaft 31 and thus the ball 32 may be reciprocally moved within the cavity 22 and this movement or rather the resulting relative spacing between the ball 32 and the Valve seat member 34 controls the flow of fluid from the cavity 22 to the spray tip assembly 14.

The other end 35 of the shaft 3l has a central bore 36 formed therein which receives, in telescoping relationship, the forward end 37 of a shaft 38. External threads are also formed on the end 35 of the shaft. A pair of nuts 39 and 40 are threaded on the end 35 of the shaft and may be adjustably positioned thereon.

The other end of the shaft 3S extends into a relatively large diameter counterbore 41 in the cap 26 and is threaded into a central bore 42 in the base 43 of the cap 26. A coil compression spring 44 is positioned about the shaft 38 and one end thereof abuts the base 43 of the cap. The other end of the coil spring 44 engages the rear nut 39 and urges the nut 39, and thus the shaft 3l and ball 32, toward the valve seat member 34. The forward nut it? is engaged by the lower bifurcated end 3i) of the crank arm 22 so that counterclockwise movement of the shaft 2? causes the shaft 31 and ball 32 to move away from the valve seat member 34 against the bias of the spring 44.

The components of valve 23 are arranged so that when the trigger is in the position shown in FlGURE l, the ball 31 tightly engages the valve seat member 34 and completely blocks the flow of fluid from the cavity 22 to the spray tip assembly 14. Movement of the trigger 15 from the position shown in FIGURE l, toward the handle 12 causes the ball 32 to be correspondingly moved away from the valve seat member 34 and thereby permits :duid to fiow from the cavity 22 to the spray tip assembly. Obviously, the amount of fluid ow is dependent on the distance the ball 31 is moved away from the member 34 and this, of course, is determined by the distance the trigger 1S is moved toward the handle 12. Also after the operator releases the trigger, the bias of coil spring 44 is sufficient to close the valve 23 and thereby stop the flow of uid.

Referring now to FGURE 2, the spray tip assembly 14 is mounted on an annular nipple 45 `formed on the forward end of the barrel 13. The nipple 45 has external threads 46 formed thereon and includes a central bore 47 and counterbore 4S, with a shoulder 49 formed therebetween. The bores 47 and 4% are coaxial and communicate with the cavity 22. The counterbore 48 is internally threaded at S1.

An annular housing 52 is threaded into the counterbore 48 and a sealing ring 53 is compressed between the telescoped end S4 of the housing 52 and the shoulder 49 to prevent iiuid leakage therebetween. The housing has a central bore 5S and counterbores 56 and 57. The bore 57 is larger in diameter and length than either of the bores 55 and 5e and, in effect, forms an elongated cavity in the housing. The tubular valve seat member 34 is positioned within the counterbore 56 and is secured therein by, for example, silver solder which additionally provides an airtight seal between housing 54 and member 34. As noted above, member 34 has a spherical seat ground on its upstream end that is substantially the same diameter as the ball 32 of the valve 23. The member 34 also includes a central bore 58 which has substantially the same diameter as bore 5S of the housing 52 and which affords a passage through which fluid may ilow from the cavity 22 to the bores 55 and 57, whenever 'the ball 32 is moved away from the seat in member 34.

A cap 59 cooperates with the threads 46 on the nipple 45 and includes dierent diameter bores 61 and 62 with a shoulder 53 therebetween. During the operation of the spray gun, a conventional spray tip 64 (not shown in cross-section) and annular gasket 65 are positioned within the bore 62 with the forward end and spray orifice 66 of the spray tip d4 extending through the bore 6l and slightly beyond the forward end of the cap 59. When the cap 59 is tightly threaded on the nipple 45 the spray tip 64 and gasket 65 are clamp-ed between the shoulder 63 and the forward end 67 of the housing 52 thereby preventing leakage between the housing 52 and the cap 59 and between the tip 64 and the cap 59. Of course, the spray tip 64 may be easily removed from the gun by simply unscrewing the cap 59.

it should be apparent from FIGURE 2 that when the ball 32 is moved away from the valve seat member 34, in response to a rearward movement of the trigger, fluid under high pressure will iiow from the cavity 22 through the bore SS is member 34, the bores 55 and 57 in housing 52, the spray orice e6 in the spray tip 64 and thus be emitted from the gun in the form of a ne mist or spray. Moreover, since the effective area of the spray orifice 66 is less than the elective area between the ball 32 and member 34, when the gun is fully triggered, the bores S3, 55 and 57 become iilled with uid during normal operation of the gun.

The novel fluid dispersion means of this invention is positioned in the bore or cavity 57 in the housing 52, and is adapted to prevent injuries which might otherwise occur by accidental or inadvertent triggering of the gun while the spray tip 64 is removed therefrom. When the spray tip 64 is removed from the gun, the bores 57 and 5S are obviously not filled with fluid, and thus fluid passing through the bores, and emitted from the gun, would be in the form of a concentrated, relatively high pressure and velocity stream if it were not for this novel dispersion means. Such a fluid stream could easily penetrate the skin of a person and thus could result in serious personal injuries.

To alleviate this hazard and to insure that the fluid stream emitted from the gun, when the spray tip 64 is removed, will not be in the form of a concentrated, high pressure stream, the housing 52 has three small diameter cylindrical pins 68, 69 and 71 positioned within the counterbore or cavity 57. These pins extend diametrically across the cavity 57 and the longitudinally axis of each pin intersects and is perpendicular to the longitudinal central axis of the cavity 57. The pins are equally spaced from each other longitudinally along the longitudinal central axis of the cavity 57 and the longitudinal axis of each pin is disposed from the longitudinal axes of the other pins by an angle of 60 degrees as shown in FIG- URE 4. The ends of the pins 68, 69 and 71 are secured by, for example, silver solder in transverse bores 72-77 drilled in the side of the housing 52 thereby providing the pins with sufficient stability and strength to withstand the force of the fluid stream impinging upon them. Since, as noted above, the housing 54 is threaded within the nipple 45, the length of the pins are selected so that the pins do not extend within the external threads 78 formed on the housing 52.

In the preferred embodiment of this invention, each of the pins 68, 69 and 71 is approximately 1/2 inch in length and has a diameter of 3/32 inch. The pins are spaced 1/s inch from each other along the longitudinal central axis of the cavity 57 which has an internal diameter of inch and a length of approximately W16 inch. The diameter of the bore 55 is approximately 3/16 inch and the diameter of bore 58 in valve seat member 34 approximately inch. The ball 32 is 1A inch in diameter and the valve seat member 34 has a 1A; inch spherical diameter impact ground or lapped seat. The dimensions of the other components of the gun are in proportion to those given above, as shown by the drawing,

The spray gun also includes, as an additional safety feature, a trigger stop assembly 79, which is mounted on the handle 12 and which may be used to prevent movement of the trigger 15 toward the handle 12.

The trigger 15 is of conventional construction and has a lower U-shaped cross-sectional portion 81 with a base 82 and rearwardly extending sides 83. The stop assembly 79 includes a thin triangularly shaped member 84 that is mounted on one end of the end of a shaft 85 which extends through a hole (not shown) in the wall 86 of the handle 12 and into the hollow interior of the handle. A nut 87 is fastened on the other end of the shaft 85 and a coil compression spring 88 is positioned about the shaft 85 with its ends abutting the wall 86 and the nut 87. An annular collar 89 is also positioned about the shaft 85, between the member 84 and handle 12. The collar 89 is mounted on the wall 86 and has four V shaped notches 91 formed on its forward edge. These notches 91 are spaced at 90 degree intervals about the edge of the collar 89.

The member 84 has a reduced portion 92 which cooperates with two of the notches 91 when the member 84 is in the position shown in FIGURE l and with the other two when member 84 has been rotated 90 degrees from the position shown in FIGURE l. The spring 88 biases the member 84 against the collar 89 and the cooperation between the notches 91 and the portion 92 prevents the member 84 from freely rotating relative to the collar.

The space between the sides 83 is large enough so that when member 84 is positioned as shown in FIGURE l, member 84 may pass therebetween without touching the sides 83. Therefore, while the member 84 is in that position, the trigger 15 may be freely moved toward the handle 12 by the operator, until, of course, the member 84 abuts the base 82. However, when member I84 is rotated 90 degrees from the position shown in FIGURE l, the sides 83 of the trigger will abut the member 84 when the operator attempts to move the trigger toward the handle 12. Therefore, in this position the member 84 prevents rearward movement of the trigger 15 and thereby prevents the emission of fluid from the gun 10.

Thus, the stop assembly 79 permits the operator of the gun 10 to render the gun inoperable while, for example, he is removing and replacing the spray tip '64. However, and unfortunately, the operators do not always remember to use the stop assembly 79. And for this reason, it is necessary to provide, as an additional means for preventing injury to the operator of the gun, the pins 68, 69 and 71 which do not require any positive action on the part of the operator to render them effective.

From the foregoing, it is apparent that the improved airless spray gun of this invention includes a novel fluid dispersion means which effectively disperses and diffuses any fluid stream discharged from the gun while the spray tip is removed. This novel dispersion means substantially eliminates the possibility that the fluid stream may be able to penetrate the skin of the operator or another person and thereby cause injury. Moreover, the novel dispersion means does not affect the normal operation of the gun or the spray patterns emitted therefrom when a conventional spray tip is used with the gun.

As noted above, the novel dispersion means comprises three pins which are positioned across the fluid passage interconnecting the fluid valve and the spray tip in the gun. The arrangement of the pins insures the complete `dispersion and diffusion of any fluid stream emitted from the gun upon accidental triggering of the gun while the spray tip is removed.

The novel fluid dispersion means is easily installed in a spray gun, is relatively inexpensive to manufacture and is completely compatible with the other components of a conventional airless spray gun.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The preferred embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing descriptions, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by the United States Letters Patent is:

1. An airless spray gun for spraying high pressure fluids comprising:

a body;

a fluid passage formed in the body;

means for connecting one end of said passage with a source of pressurized fluid;

a spray tip;

means for removably mounting the spray tip on the other end of said passage whereby the fluid passing through said passage will be sprayed through the tip and from said body in a predetermined pattern;

a valve seat in said passage between the ends thereof;

a valve member positioned in said passage and cooperating with the seat to control the flow of fluid through said passage; and

means positioned in said passage between the seat and the other end of said passage for dispersing and diffusing the fluid flowing through said passage while the spray tip is removed from the body.

2. The airless spray gun described in claim 1 wherein the dispersion means projects into said passage downstream from the valve seat.

3. The airless spray gun described in claim 2 in which said dispersion means includes at least one pin projecting into said passage.

4. The airless spray gun described in claim 2 wherein the dispersion means includes at least one pin projecting into said passage with both ends thereof secured to the side of said passage, the longitudinal axis of the pin being perpendicular to and intersecting the longitudinal central axis of said passage.

5. The airless spray gun described in claim 2 in which the dispersion means includes three pins projecting into said passage, each pin intersecting the longitudinal central axis of said passage.

6. The airless spray gun described in claim 2 wherein the dispersion means includes at least three pins which are spaced from each other along said passage, the longitudinal axes of the pins being perpendicular to and intersecting the longitudinal central axis of said passage and being displaced by an angle of approximately 60 degrees.

7. The airless spray gun described in claim 3 in which both ends of the pin are mounted in the side of said passage.

8. The airless spray gun described in claim 3 in which the longitudinal axis o the pin is substantially perpendicular to the longitudinal aXis of said passage.

9. The airless spray gun described in claim 3 in which the pin intersects the longitudinal central axis of said passage.

lil. The airless spray gun described in claim 5 in which both ends of each pin are mounted in the side of sai-d passage.

11. The airless spray gun described in claim S in which the longitudinal axis of each pin is substantially per pendicular to the longitudinal central axis of said passage 8 and the pins are spaced from each other along said passage.

l2. The airless spray gun described in claim 5 in which the longitudinal axes of the pins are displaced by an angle of approximately 60 degrees.

References Cited UNTTED STATES PATENTS M. HENSON WOOD,

H. NATTER, Assistant Examiner.

JR., Primary Examiner. 

1. AN AIRLESS SPRAY GUN FOR SPRAYING HIGH PRESSURE FLUIDS COMPRISING: A BODY; A FLUID PASSAGE FORMED IN THE BODY; MEANS FOR CONNECTING ONE END OF SAID PASSAGE WITH A SOURCE OF PRESSURIZED FLUID; A SPRAY TIP; MEANS FOR REMOVABLY MOUNTING THE SPRAY TIP ON THE OTHER END OF SAID PASSAGE WHERE BY THE FLUID PASSING THROUGH SAID PASSAGE WILL BE SPRAYED THROUGH THE TIP AND FROM SAID BODY IN A PREDETERMINED PATTERN; A VALVE SEAT IN SAID PASSAGE BETWEEN THE ENDS THEREOF; A VALVE MEMBER POSITIONED IN SAID PASSAGE AND COOPERATING WITH THE SEAT TO CONTROL THE FLOW OF FLUID THROUGH SAID PASSAGE; AND MEANS POSITIONED IN SAID PASSAGE BETWEEN THE SEAT AND THE OTHER END OF SAID PASSAGE FOR DISPERSING AND DIFFUSING THE FLUID FLOWING THROUGH SAID PASSAGE WHILE THE SPRAY TIP IS REMOVED FROM THE BODY. 